The transient removal of CTLA-4-mediated inhibition (CTLA-4 blockade) can induce effective anti-tumor immunity. Efficacy of CTLA-4 blockade as a single agent has been shown in melanoma 53. It has been hypothesized that anti-CTLA-4 antibody might deplete Treg cells 54, inducing autoimmunity. However, patients receiving Ipilimumab have not shown a decrease in Treg number or function in peripheral blood 55.